Micrometer-calipers.



l. A. DAVIDSON.

MICROMETEB CALIPERS.

APPLICATION FILED APR.30. 191s.

Patented Jan. 14, 1919. I

WIT/VESSES A TI'ORNEYS i UMTED srnrns PATENT ormoni.

JOSEPH ALLAN DAVIDSON, 0F INDIANAPOLIS, INDIANA.

MICROMETER-CALIPERS.

To all 'whom z't may concern:

Be it known that I, JOSEPH A. DAVIDSON, a citizen-of the United States, and a resident of Indianapolis, in the county of Marion and State of Indiana, have invented certain Anew and useful Improvements in Micrometer-Calipers, of which the following is a specication. e

My present invention relates particularly to micrometer calipers, my object being the provision of eective and efficient means in connection therewith and in the nature of adjustable pressure controls whereby to obviate further movement of the registering thimble when a predetermined pressure on the article being measured has been reached.

In explanationof this object and by way of a general outline of the present invention, it may be noted that although micrometer calipers which have long been in use, are extremely accurate to small fractions, it is equally well known that the readings are susceptible of variations in the hands of different persons due to the different degree of pressure of the spindle against the work. In other words, it is very unusual for different persons, using the same instrument on the same work, to register the same measurements.

Measurements are registered in calipers of this type, in connection with a longitudinal scale on the barrel and the circular scale on the thimble, as the spindle is advanced to engage the work between its inner end and fthe usual stationary anvil. In accordance with my invention, I provide a handle for rotating the thimble together with means whereby when `the lspindle engages the work with a predetermined pressure, the registering thimble can no longer be rotated by the use'of the handle.

In the accompanying drawings illustrating my present invention,

Figure 1 is an elevation, partly broken away and in section, illustrating one form of my invention.

Fig. 2 is a side elevation thereof.

Fig. 3 is a horizontal section taken substantially on the line 3 3 of Fig. 1.

Speccation of Letters Patent. Patented UL 14, 1919 Application filed April 30. 1918.

Serial No. 231.650.

Fig. 4 is a side view partly in elevation and partly in section illustrating ya slightly y modified form.

Fig. 5 is a side view partly in elevation and Vpartly in section illustrating another modified form.

Figs. 6 and7 are sectional views taken on line 6-6 of Fig. 5, looking in relatively opposite directions. Y

Referring nov7 to these gures, and particularly to Figs. 1 to 3 inclusive, my invention has to do with the usual form of micrometer calipers which include a substantially U-shaped frame 10, one extension of which supports a stationary anvil 11, and the other extension of which supports an extending barrel12 which is internally threaded and receives a spindle 13 in-co-aXial relation to the anvil 11 and whose inner end lopposes theanvil within v Fig. 2 and the thimble 14 having a circular scale 16 around its inner end.

According to the form of my invention as shown in Fig. l, the spindle 13 has an axial borein which is slidably disposed a pressure stem 17, the outer end of the thimble 11 being chambered to provide an annular space 18 closed by an end cap 19y which is threaded on the thimble 14 and within which is an upstanding rib 20 around the outer end of the bore of the spindle 13.

At its outer end the pressure stem 17 is provided with a laterally projecting lug 21 which normally seats within the recess of the rib 20, the outer end'ofsaid stem being joined to a handle 22 having an axial bearing in the cap 1 9 and having a knurled exteriorly projecting portion 23. Thus in the normal position of the parts, the operator grasping the knurled handle 23 rotates the thimble 14, by virtue of engagement of the lug 21 within the recess of rib 20 as seen in Fig. 3, until the inner end of the stem 17 which normally projects beyond the inner end of the spindle 13, is moved by virtue of its contact with the Work to a position flush with the inner end of the spindle at which time stem 17 Will have been shifted longitudinally a suflicient distance to move its lug 2l entirely free of the rib 20, the handle 23 then rotating free Without farther advancing thimble 14.

In "this Way, the same reading Will be had by any number of persons using the instrument upon the same Work as it is simply a question of rotating the handle until farther radvance of the registering part becomes impossible by the use of the handle.

instead of using a stem Within the spindle as previously described, I may provide the thimble 14a as seen in Fig. il with an inner sleeve 24C externally threaded to screvvr Within the barrel l2, and I may use a longitudinally movable spindle 13a connected `alt its outer end to a knurled handle 23a and provided with a lug 21a normally extending Within the recess of a rib 20L which latter is located Within the chambered end of the thimble lila in the same manner as previously described in connection with Fig. 1.

Thus according to the form of Fig. 4f, the spindle itself is longitudinally movable until the lug 211 disengages so that the thimble if? cannot be farther advanced by rotating the handle.

According to the form of the invention shovvn in Fig. 5, the spindle 13b has a splined connection along its inner portion with the inner end of the barrel 12b so that it may move longitudinally, but will be held against rotation, the outer end of this spindle having a head 25 located Within the outer chambered end of the thimble 14.". in this construction, the handle 23D may be formed integral With the cap 19h, the inner surface of which cap has segmental ribs 26 the spaces between the ends of which are adapted to receive lugs 27 projecting from the spindle head as Will be seen by reference to Figs. 6 and 7. rThe thimble 14h is rotated by the handle 27h as in the previous forms unt-il pressure of the inner end of the thimble 13b causes suflicient longitudinal movement thereof to shift the lugs E27 of its outerv head 25 between the segmental ribs 26 of the cap 19h, at Which time the parts Will be locked and further registering movement of the thimble 14h thereby prevented.

It is obvious from this description that each of the several forms of the invention described Will operate to eifectively and eiiiciently bring about the desired results and completely fulfil the objects first above stated.

I claim l. The combination With a micrometer caliper having a frame, a barrel carried by the frame, a thimble having a threaded connection With the barrel, and a spindle movable in the thimble, of means for preventing advancing movement of the spindle under actuation of l`the thimble When apredetermined pressure on an article being measured has been reached.

2. The combination with a micrometer caliper having a frame, a barrel carried by the frame, a rotatable thimble in threaded connection With the barrel, and a spindle movable through the thimble, of a member for rotating the spindle having a yielding connection with the barrel including connecting members movable out of enga-gement With one another when a predetermined pressure of the spindle upon an article being measured has been reached.

3. A micrometer caliper including a frame having an anvil at one side and a barrel at its opposite side, a thimble in threaded engagement With the barrel and having a chambered outer end, a spindle movable through the barrel in co-aXial relation to the anvil, and a handle at the outer end of the thimble, said handle and said thimble having relatively movable connecting members located in the chamber of the thimble for the purpose described.

4. A micrometer caliper comprising a frame, a barrel carried by the frame, a thimble movable on the bar-rel and having a threaded connection therewith, a handle located at the outer end of the thimble for rotating the same, said thimble and said handle having relatively engaging ribs and recesses, and Work engaging means movable axially through the barrel and in connection with said handle for shifting the latter out of connection With the thimble when a predetermined pressure on an article being measured has been reached.

JOSEPH ALLAN DAVIDSON.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

